Generally, a circuit board comprises a circuit pattern formed along a substrate, and a connecting portion which is connected to the circuit pattern and has straight conductors extending toward an edge portion of the substrate, and the circuit board is electrically connected to other circuit board or the like through this connecting portion.
Conventionally, for electrically connecting the circuit board to other circuit board, there have been adopted a structure of fixing a connection part such as a connector to the connecting portion or a structure in which a connecting portion of the other circuit board is stacked on the connecting portion in facing relation, and the connecting portions are connected together by soldering or the like.
In recent years, in order to omit the connection part and a soldering process, there has been proposed a connecting structure in which connection portions of circuit boards are disposed in facing relation, and the connection is fixed by an adhesive.
In such a connecting structure, in order to obtain a conductive connection between the connecting portions, the circuit boards have been pressed against each other along a direction of stacking of the circuit boards, thereby forcing the adhesive, residing between the connecting portions, out from between conductors.
Incidentally, in order to obtain a good conductive connection between the connecting portions, it is necessary to positively force the adhesive out from between the conductors of the connecting portions so that the conductors can positively contact each other.
In order to satisfy such a requirement, for example, an electrical connection method and a liquid crystal display device (Patent Literature 1) in which plating bumps or the like of a convex shape are provided on conductors of a connecting portion to form partial contact points, and the forcing-out of an adhesive is effected satisfactorily, thereby obtaining a conductive connection between the conductors, or a flexible wiring sheet joining method (Patent Literature 2) in which a rigid support member having continuous projections is located, and insulating covering layers of a thermoplastic resin are fused by heat, and upper and lower sheets are mechanically connected together, and also wirings are electrically connected together, thereby effecting the joining, or others have been proposed.    Patent Literature 1: JP-A-10-96944 Publication    Patent literature 2: JP-A-5-205841 Publication